Bacteria and visruses. Bacterial and viral diseases.

Bacteria (to be) _____ a major group of living organisms. Many pathogens, disease-causing organisms, (to be) ______ bacteria. Most (to be) _____ minute. The first bacteria (to observe) ______________ by Anton van Leeuwenhoek in 1676 using a microscope of his own design.

All bacteria (to have) __________ a relatively simple cell structure. They (to lack) _________ a cell nucleus and organelles. The most important bacterial structural characteristic (to be) _______ the cell wall. Bacteria can (to divide) __________________ into two groups (Gram positive and Gram negative).

Bacteria (to reproduce) _______________ through asexual reproduction which (to result) ___________ in cell division.

Certain types of bacteria (to be) _______ also capable of sexual reproduction through bacterial conjugation.

Bacteria (to be) ______ both harmful and useful to the environment, and animals, including humans. The role of bacteria in disease and infection (to be) ____ important. Some bacteria (to act) ______ as pathogens and (to cause) _________ tetanus, typhoid fever, pneumonia, cholera, foodborne illness, and tuberculosis(TB).

Bacteria, often in combination with yeasts [‘ji:sts] and molds [mouldz], (to use) ____________ in the preparation of fermented foods such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine, and yogurt. Using biotechnology techniques, bacteria can (to bioengineer) ____________________ for the production of therapeutic drugs, such as insulin.

Virus (to be) ______ a submicroscopic parasitic particle that infects cells in biological organisms. The study of viruses (to be) ____ virology.

Viruses (to be) ______ intracellular parasites. They (to lack) _______ the cellular machinery for self-reproduction.

Viruses (to be) ______ non-living particles. They can only (to replicate) __________ when an organism (to reproduce) _______________ the virulent RNA or DNA. Viruses (to discover) ____________________ by Robert Hooker who (to use) _____________ the first microscope.

Because viruses (to be) _______ acellular and (not to have) ________________ their own metabolism, they must (to utilize) ____________ the machinery and metabolism of the host for the purpose of self-replication.

Examples of diseases caused by viruses (to include) ____________ the common cold, smallpox; AIDS, etc.

Detection and subsequent isolation of viruses from patients (to be) ________ a very specialised laboratory subject. Normally it (to require) ______________ the use of large facilities, expensive equipment, and highly trained specialists such as technicians, molecular [mou’lekjule] biologists, and virologists.

The most effective medical approaches to viral diseases (to be) _______ vaccination to provide resistance to infection, and drugs that (to treat) _____________ the symptoms of viral infections. Patients often (to ask) _______ for, and GPs often (to prescribe) _________________ antibiotics, which (to be) _________ useless against viruses, and their misuse against viral infections (to be) _______ one of the causes of antibiotic resistance in bacteria.

Worldwide mortality due to infectious diseases
Rank	Cause of death	Deaths 2002	Percentage of all deaths	Deaths 1993	Rank 1993
N/A	All infectious diseases	14.7 million	25.9%	16.4 million	32.2%
1	Lower respiratory infections	3.9 million	6.9%	4.1 million	1
2	HIV/AIDS	2.8 million	4.9%	0.7 million	7
3	Diarrheal diseases	1.8 million	3.2%	3.0 million	2
4	Tuberculosis (TB)	1.6 million	2.7%	2.7 million	3
5	Malaria	1.3 million	2.2%	2.0 million	4
6	Measles	0.6 million	1.1%	1.1 million	5
7	Pertussis	0.29 million	0.5%	0.36 million	7
8	Tetanus	0.21 million	0.4%	0.15 million	12
9	Meningitis	0.17 million	0.3%	0.25 million	8
10	Hepatitis B	0.10 million	0.2%	0.93 million	6
11-17	Tropical diseases (6)[9]	0.13 million	0.2%	0.53 million	9, 10, 16-18
Note: Other causes of death include maternal and perinatal conditions (5.2%), nutritional deficiencies (0.9%), noncommunicable conditions (58.8%), and injuries (9.1%).

Influenza [,influ’enze(to know) ________________commonly known as the flu or the grippe [grip]. Flu (to be) _____ a contagious disease of the upper airways and the lungs. It (to cause) __________________ by viruses. It rapidly (to spread) _________ around the world in seasonal epidemics. It (to kill) __________ millions of people in pandemic years and hundreds of thousands in nonpandemic years. It (to create) ___________ health care costs and lost productivity.

The virus (to attack) _______________ the respiratory tract. It (to transmit) ________________from person to person by saliva droplets expelled by coughing/ The virus (to cause) ________ the following symptoms:

• Fever

• Headache

• Fatigue/Sore joints (can be extreme)

• Dry cough

• Sore throat

• Nasal congestion

• Sneezing

• Irritated eyes

• Body aches

• Extreme coldness

Recovery (to take) _________________ about one to two weeks. Influenza can (to be) _______ deadly, especially for the weak, old or chronically ill. Some flu pandemics (to kill) _________ millions of people.

Influenza (to reach) ________ peak prevalence in winter

It (to be) _____ possible and in many cases (to recommend) ______________ to get vaccinated against influenza with a flu vaccine. Flu vaccine (to be) ________ available as nasal spray vaccine (recommended for all healthy people ages 5 to 49) and as injectable vaccine. It (to be) ______ possible to get vaccinated for the season and still catch the flu.

If you (to get) ______ the flu, get plenty of rest, drink a lot of liquids, and avoid using alcohol and tobacco. You can (to take) _________ medications such as acetaminophen to relieve the fever and muscle aches associated with the flu. Children and teenagers with flu symptoms (particularly fever) should (to avoid) ___________ taking aspirin. Taking aspirin in the presence of influenza infection (especially influenza type B) can (to lead) __________ to Reye syndrome, a rare but potentially fatal disease of the liver. Influenza (to be) ___________ an extremely variable disease. It (to find) _______________also in pigs (swine flu), birds (bird flu), and other animals. The natural host for avian influenza virus (to be) _______ aquatic [e’kwaetik] birds. The current avian flu threat (to be) _____ due to the H5N1 virus.

Tonsillitis (to be) ____ an inflammation of the tonsils in the mouth. It often (to cause) ___________ a sore throat and fever. It may (to cause) _______ by Group A streptococcal bacteria. Most tonsilitis however (to be) _____ viral in origin. Treatment (to consist) ____________ of painkillers and fluids. If tonsilitis (to cause) _____________ by bacteria then antibiotics (to prescribe) _________________. Usually penicillin (to use) ____________ . Erythromycin (to administer) _________________ if the patient (to be) ____ allergic to penicillin. When tonsillitis (to cause) ______________ by a virus, the length of illness (to depend) _____________ on which virus (to involve) __________. Usually, a complete recovery (to make) _____________ within one week.

An abscess may (to develop) ___________ during an infection, typically several days after the onset of tonsillitis. This (to term) ____________ a peritonsillar abscess (or quinsy).

In chronic cases or in acute cases, a tonsillectomy can (to perform) ____________ to remove the tonsils. Patients whose tonsils (to remove) __________________ (to protect) __________ still from infection by the rest of their immune system.

Hypertrophy of the tonsils can (to result) ______________ in snoring, mouth breathing, disturbed sleep, and obstructive sleep apnea, during which the patient (to stop) ___________ breathing and (to experience) _________________ a drop in the oxygen content in the bloodstream. A tonsillectomy can (to be) ________ curative.